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Light-directed activities: Order fulfillment at the speed you need

Rooted in increasingly complex software, the concept of pick-to-light has moved well beyond the pick and is now capable of relaying an array of information to workers throughout the fulfillment process.
May 01, 2013

Ten years ago, most cell phones had single-color displays, and they were primarily used to make phone calls. Now glance at the phone in your pocket, think about its capabilities beyond dialing a number, and you will have some sense of the transformation of light-directed order fulfillment technology over the last decade. Whether stationary or cart-based, approaches such as pick-to-light, put-to-light, pack-to-light, pick-to-screen, and dozens of other variations are enabling radically different product flow through a facility.

“There is a level of creativity that now exists,” says Chris Castaldi, manager of business development for W&H Systems. “Before, there was the specific process of pick-to-light and essentially one way that it worked. Now we can decide how to get the best value out of lights in a variety of applications.”

Although a potentially transformational technology, not all successful light-directed applications require extensive reworking of existing fulfillment processes, says Ken Ruehrdanz, manager of the distribution systems market for Dematic.

The best solutions follow a crawl, walk, run progression with lights deployed to address specific stock keeping unit (SKU) profiles and bottlenecks. Mobile light-enabled carts and put walls for order consolidation can be targeted to improve speed and accuracy at any step in a picking application. Both upstream and downstream of the pick, light-directed technology can take the guesswork out of fast and precise product movement.

Pick-to-light and goods-to-person
If light technology is intended to increase the speed with which a picker locates and places each item, it follows that the best way to keep the picker productive is to keep them picking, not walking. Castaldi suggests that light-directed picking “is a game of seconds, which turn into minutes, hours and dollars.” Therefore, goods-to-person technology is an increasingly fundamental practice to effective light-picking solutions.

“Things can be slightly random in a pick-to-light environment,” says Gary Cash, vice president of design services for Wynright. “Even if lights are activated in sequence, these setups might still place a burden on the operator to determine the most efficient path. With goods-to-person, I can determine exactly what sequence in which I want to present product to the picker.”

Carousels, for example, are a natural fit for light-directed technology. In fact, George Fiorentino, East Coast director of sales and business development for Sapient Automation, says, “I don’t sell a single carousel or vertical lift module (VLM) for picking that doesn’t include light direction of some kind.”

In some carousel applications, the takeaway conveyor—located behind the worker as he faces the carousel—can be supplemented with flow rack locations above and below. “When the operator begins an order, he immediately has fast-moving items to pick from light-directed flow rack as the carousels present the next item,” says Fiorentino.

Bringing goods to the picker can boost that person’s productivity, but it can also impact the facility’s overall approach to storage and inventory, according to Kevin Reader, senior account executive with System Logistics. Typically, the speed of light-directed technology and the ability to address more than one order at a time make it suited to high-volume items.

“With goods-to-person, you could address the slow movers in the same space as fast movers and conceivably combine and collapse reserve storage and primary storage into one medium,” Reader says. “That can make for a much more efficient, waveless warehouse, with sustained picking rates of 600 lines per hour. I think that’s a real game-changer.”

Put-to-light and the put wall
Whether fed by manual batch pickers or an automated storage and retrieval system (AS/RS), setups where SKUs are in motion and orders stay in place lend themselves to put-to-light technology. At its most basic, a put-to-light approach delivers a carton or tote of a single SKU to a stationary operator who picks what he needs for active orders. Depending on the average line count and cube of those orders, an operator might be picking from a single SKU to a dozen or so simultaneous order locations, each with its own light bar, or with one screen directing all orders.

At the other end of the order cube spectrum, the customer might benefit from a put wall, a series of open-ended cubbies housing 50 or more dynamic order locations. Lights on the backside of the put wall alert the packer when each order is complete. Light prompts on the packer’s takeaway conveyor might indicate the appropriate size box for the order, says Castaldi, while allowing final weighing and freight rate shopping to occur just moments before the package leaves the building. The packers’ lights might also direct them to include various promotional material or other value-added items.

Because they are effective in a range of process steps, lights can either facilitate dramatic change in product flow or slow, incremental change in a facility. A light-directed pick station, put wall or mobile light-enabled pick cart can be folded into the current picking process to better address certain SKU and order profiles. Lights have also evolved and expanded alongside voice-directed technology. “It was thought that perhaps voice would replace lights, but in actuality, voice complements lights and allows more applications for both technologies,” says Dematic’s Ruehrdanz.

For example, in a traditional carton-to-store, pick-to-voice environment, a relatively small area of floor space could be designated for a light-directed put wall. A voice or light-directed pick cart might make a pass through the warehouse and fill a number of totes with SKUs for multiple orders before depositing them at the put wall for consolidation.

Consolidation and decoupling
The concept of order consolidation is rooted in the decoupling of steps in the order fulfillment process. In traditional batch picking, a single person is usually responsible for an entire order, and their paths through a warehouse will reflect that. Light technology’s emphasis on speed and accuracy means it can be deployed in targeted areas of a process as needed, allowing a batch picker to fulfill some or most of an order before a worker at a put wall completes or consolidates it. By enabling a fast and accurate means of sortation, light can also allow for added process steps while reducing the likelihood of error.

For instance, Todd Sherbinow, senior product manager for Lightning Pick Technologies, a Matthews International Company, has a customer who performs value-added services to items. The customer stocks several hundred SKUs of base product, which can become many thousands of SKUs as they become customized. The warehouse management system (WMS) will batch 10 direct-to-consumer orders, which are picked by light. Those batches are then sub-batched by workflow, with one group sent to stamping, one to embroidering, and one that stays generic. Then they are driven back to a light-directed put wall station for consolidation.

“Mass customization and speed are the key business drivers,” says Sherbinow. “They try to offer that sort of personalization and still maintain same-day ship objectives.”

Although light can be brought to product as needed, Wynright’s Cash says the placement of inventory at the outset should be shaped according to the capabilities of the light hardware. “The key to making these products successful is to move your SKUs around and get the right SKUs in front of the right technology,” he says. “If your slow-movers are in front of pick-to-light, it will not be successful.”

The light-directed order-filler
The picking rates of a stationary, light-directed order filler will be hard to beat. Although a goods-to-person system might be simple and low-cost or require significant capital investment and be highly automated, it’s not for every application. The zone-based pick module, a staple of traditional pick-to-light applications, has not escaped change as light hardware has evolved. With multicolored lights, what were once rigidly defined zones can now be shared by neighboring workers, or staffed by as many employees as is necessary to address spikes in volume.

“If the size of the zones can be flexed in real time, this gives you the ability to do true bucket brigade-type fulfillment,” says Lance Reese, director of technical solutions, order fulfillment for Intelligrated. Reese also highlights the concept of the “next best task,” where depending on order volume a picker might be directed to pack an order out, perform replenishment, or conduct a cycle count. “Light-directed order-fillers are now empowered to control the areas in which they work,” says Reese.

Each order or order filler might be assigned a color, and if one SKU’s light bar is capable of signaling picks to more than one color, the number of SKU locations has effectively doubled. Taking the concept of accountability one step further, some systems might even have a wrist-mounted RFID tag that can identify the person who extinguishes a light when the person’s hand is in proximity. Additionally, light software might direct the order conveyor to “follow” the operator as he or she moves through a zone.

Each worker can also be made more productive by light bars that span an entire shelf, as opposed to lights placed at 1-foot intervals designating fixed product lanes. The lights can dynamically indicate flexible SKU locations, maximizing SKUs per shelf and minimizing worker travel time to each item.

“In the past, the idea of changing every bar code label and light bar to accommodate changing SKU mixes was an opportunity for errors,” says Reese, who says such adjustments were painful when done quarterly, much less in real time. “Now there are light devices that can be used on the back side of the shelf to inform replenishment to match the dynamic shelf bars on the pick side.”

Typically in pick-to-light, the operator doesn’t have an opportunity to signal a replenishment, other than the occasional short. “Now, you can be a little more proactive,” says Cash. “Ideally, you will never see a short, whereas in older systems it would be all too common. Or, to avoid it, replenishment might consist of someone roaming around the rear side of the flow racks looking for low SKUs without any real guidance.”

Real-time orientation
From its roots in monochromatic, alphanumeric displays, light technology has come a long way. But each additional color and each additional layer of data communicated to the worker requires an exponential increase in software complexity. And since light picking is all about speed, real-time orientation is essential. Although not every customer’s order profiles are ideal for pick-to-light, System Logistics’ Reader argues most will benefit from systems with real-time capabilities.

“Real-time data and order-management is no longer a driver, it’s an ante,” says Reader. “Look what’s happening with the push to same-day delivery. If you can’t increase your order window until later in the day, that’s a real competitive problem.” Reader estimates that although just 25% of end users are at that level now, the number is quickly going nowhere but up.

Real-time capabilities enhance the responsiveness of zone-based pick- and put-to-light modules as well as goods-to-person stations, but it can also enhance an operation’s nimbleness throughout a facility. Cart-based light picking systems can roam into voice-pick areas, and vice versa, to respond to hot orders, rush orders or one-off orders in a concept Sherbinow calls “overlay.” And if the cart operator can accept new orders in real time, then the worker who happens to be in front of the SKU at the right time can grab it while he’s there.

Any overlay of light, voice, or any other picking technology demands robust software. Sherbinow is careful to emphasize the importance of deploying light technology on a common platform with other order fulfillment systems. “Smooth interoperability is rarely achieved by light software that must communicate with independent voice and WMS software, for instance,” says Sherbinow, who says light-directed software platforms might also include some level of conveyor control and labor management. “If everything works on the same database and platform, the customer has a single point of interface. As order waves come to the software, it manages the technology in different areas, but it all appears the same to the end user.”

Companies mentioned in this article
Lightning Pick:
Kardex Remstar:
Sapient Automation:
System Logistics:
W&H Systems:

Airline enjoys heightened productivity

Jazz Aviation is a regional air carrier traveling to and from approximately 80 destinations across Canada and the United States. The Jazz operational base in Toronto, Ontario, is responsible for maintenance and repair operations for 125 airplanes, 24 hours a day, seven days a week. After the company installed light-directed vertical lift modules (VLM) in the maintenance stockroom, it was able to more efficiently supply parts to technicians on site as well as to five other bases.

With 20,000 SKUs in inventory, Jazz has to keep a close eye on each part coming in and out of the stockroom. Accuracy and traceability are essential to identify what part number and batch number is used in each airplane. Before the VLMs, the 6,900-square-foot facility already had 200 bays of shelving with no floor space available.

In the old shelving area, it took four to seven minutes per pick, producing about 15 picks per hour. “Our employees often had to sort through 50 parts to find the correct batch number,” says Mike Hauser, stores system manager. “It was a time-consuming and labor-intensive process.”

Roughly 1,196 square feet of shelving and half of the 20,000 SKUs were consolidated into two shuttle VLMs (Kardex Remstar, that together occupy just 184 square feet. Operated by a single employee, the VLMs are located alongside a four-position batch station, where additional pick-to-light technology and label printers add inventory control and increased accuracy levels.
Using the light-directed VLMs, pick time has increased to an average of one minute per pick, or about 60 picks per hour—a productivity increase of 77%. If an order requires inventory from both the VLM area and the shelving area, the VLM parts are picked first, then shelved parts are matched up with the order at a staging area where orders are held for pickup.

Inventory in the two VLMs is managed with inventory management software integrated with the customer’s existing software. If there are 10 of the same part number in three different batches, the software will store that part in three separate locations in the VLMs. Due to the batch picking process and batch validation, accuracy has increased to nearly 99%.

“We are planning to add a third shuttle VLM to maintain growth and further increase our efficiencies,” says Hauser, who says similar automation is being evaluated at other Jazz Aviation facilities.

Light-directed picking facilitates e-commerce fulfillment
Cosmetic company Bare Escentuals operates a distribution center serving 200 retail store boutiques and 1,400 spas. To improve its warehouse logistics configuration, the company implemented a new process for picking split-case items.

The company once filled orders for spas and retail store boutiques using paper pick lists and carts. Associates pushed carts through the warehouse, one discrete order at a time. Each operator picked about 85 pieces per hour, not including packing. A dedicated team was used for packing the orders at a rate of approximately 110 pieces per hour, per operator. When peak season occurred, order fulfillment time became extended and the company had to pay for expedited shipping service to meet promised delivery dates.

The centerpiece of the new picking solution consists of a light-directed order fulfillment system integrated with a zone route conveyor network and warehouse control system (Dematic, Today, the warehouse control system (WCS) manages and directs the entire picking process with efficiency and operational flexibility, eliminating the need for paper pick lists.

The WCS software serves both order fulfillment systems with real-time control. Using the browser-based interface, supervisors can verify order contents and make adjustments to ensure an order is shipped complete. The software maintains comprehensive statistics so supervisors know exactly how many orders, lines and pieces each operator handles. Orders can be put on hold and then released to an “active” from a “pending” order pool, and SKUs can be slotted in multiple locations to facilitate workload balancing. The number of operators picking to lights or voice is allocated per shift depending on order volume.

Using the existing software, voice-directed picking was added for the e-tail channel, which shares the same inventory of 1,000 to 1,200 SKUs in reserve storage with the spa/boutique channel. The e-tail order fulfillment system is centered around batch pick carts and voice-enabled operators. Each batch pick cart accommodates approximately 20 customer orders for each trip through the picking aisles. Each order is picked into and shipped using one of three standard carton sizes, with small cube orders shipped in a bag. When the picking process is complete, the cartons are delivered to pack stations where each order is audited.

Operators stay in one zone, following pick-to-light technology to fill orders. Using one carton size for all orders, a conveyor system transports the shipping containers only to zones where there are picks. As a result, each operator can pick 500 pieces per hour on average. The system fills and ships approximately 600 customer orders, about 75,000 pieces, per day. In addition, the packing function is provided by the order picker, eliminating pack stations from the process. Order accuracy has improved by 50%.

The order fulfillment system is modular and expandable, which allowed the company’s e-tail channel order volume to quickly grow from 2,500 to 3,000 orders per day. During special promotions and holiday peak periods, order volume can be three or four times the normal volume.

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About the Author

Josh Bond, Contributing Editor
Josh Bond is Senior Editor for Modern, and was formerly Modern’s lift truck columnist and associate editor. He has a degree in Journalism from Keene State College and has studied business management at Franklin Pierce University.

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